Characteristics and Quality of Japanese Traditional Fermented Soybean (Natto) from a Low-phytate Line

The Japanese traditional fermented soybean or "natto", a cheap and nutrient-rich food, is very popular in Japan. The low-phytate (LP) soybeans exhibit higher mineral bioavailability; however, their use in preparing natto has not been reported. Therefore, in this study, characteristics and quality of natto prepared using LP soybean were investigated. The findings revealed a better color, lower stickiness, and lower hardness and taste of LP natto with lower phytate and higher inorganic phosphorus (Pi) concentrations than those in the normal-phytate (NP) natto. However, the Ca, Mg, and K concentrations were not significantly different between LP and NP natto, whereas the protein level in NP natto was slightly higher than that in LP natto. These findings indicate that the lower phytate content in LP natto than that in NP natto, could facilitate a higher bioavailability of P and other minerals. Moreover, the improved color and lower stickiness, in addition to lower hardness and taste of LP natto, imparted through improved manufacturing process could increase its acceptability overseas, thereby increasing its commercial value. These improved qualities of LP natto could contribute to improving human health as well as increasing sustainable food and nutrient security.